Hersh's story in the April 17 issue of the New Yorker magazine says that President George W. Bush and others in the White House increasingly sees "regime change" in Tehran as the ultimate solution to the unclear confrontation with Iran.

The White House believes that the only way to solve the standoff is "to change the power structure in Iran, and that means war," the Pulitzer prize-winning journalist quotes an unnamed senior Pentagon adviser as saying.

According to the report, the Bush administration has increased secret activities in Iran and has initiated a series of talks on its plans with "a few key senators and members of Congress."

The military believes a bombing campaign against Iran would humiliate the leadership in the Islamic state and lead the Iranian public to overthrow it, the report quotes a former senior defense official as saying.

The report also says that the U.S. military is considering the possible use of a B61 nuclear "bunker-Buster" bomb against Iran's main centrifuge plant at Natanz.

The United States has said it has been seeking to settle the impasse over Iran's nuclear program through diplomacy but has not ruled out an attack.

Washington accuses Iran of secretly pursuing nuclear weapons, but Iran rejects the charge, saying its nuclear program is for peaceful purposes.